Field of the Invention
The present invention is directed to a novel spin chuck system having interchangeable spin chucks of varying sizes. The system is designed for easy adaptation to accommodate the wide variety of substrates utilized in spin-coating processes.
Description of the Prior Art
When spin coating substrates, especially microelectronic substrates, the substrate must be held securely while spinning. Typically, this is achieved by using a spin chuck (also called a “spin coater chuck”), which holds the substrate in place using vacuum and/or physical tension. Vacuum is transferred to the substrate via grooves or holes in the spin chuck that are connected to a vacuum source, usually through an opening in the spindle of the spin coater.
It is often beneficial to be able to use multiple sizes of spin chucks on a single spin coater. This allows multiple-sized substrates to be coated on the same piece of equipment. Different spin coater models use different methods to enable the user to change the spin chuck on the tool. Some spin chucks use a screw in the center of the spin chuck to attach the spin chuck to the top of the spindle. Often, this screw has a hole through the middle that allows vacuum to be pulled across the surface of the spin chuck and down through the spindle of the spin coater. This design requires a screwdriver or allen wrench in order to change the spin chuck, and also creates a recessed area in the center of the spin chuck that can cause a dimple in the center of the substrate when vacuum is pulled. Because the specialized screw is also easily lost, especially down the drain port of the spin coater, the screw itself can cause delays. Other spin chucks slip over the spindle and use some sort of mechanism for locking it to the spindle and/or o-rings in order to transfer vacuum and hold the spin chuck in place. However, these designs have drawbacks because it can be difficult to see if a spin chuck is seated correctly, and chemical or wear damage to the o-rings can cause vacuum or process failure. Additionally, different spin chucks may be machined to different heights or may sit at different heights due to the installation technique, potentially causing variations in coating quality and thickness.